A wavelength-converting film and a light emitting device and a display device using the same are disclosed. The wavelength converting film comprises a fluoride phosphor powder with a Mn.sup.4+ as an activator, wherein the fluoride phosphor powder with the Mn.sup.4+ as the activator comprises a sheet-like crystal and has a chemical formula of A.sub.2[MF.sub.6]:Mn.sup.4+, wherein A is Li, Na, K, Rb, Cs, NH.sub.4, or a combination thereof, and M is Ge, Si, Sn, Ti, Zr, or a combination thereof.

A fluoride phosphor including a sheet-like crystal and a manufacturing method and an application therefore are disclosed. The fluoride phosphor has a chemical formula A.sub.2[MF.sub.6]:Mn.sup.4+, with Mn.sup.4+ as an activator. The A is Li, Na, K, Rb, Cs, NH4 or a combination thereof. The M is Ge, Si, Sn, Ti, Zr or a combination thereof. The sheet-like crystal has a thickness d. A crystal flat surface of the sheet-like crystal has a maximum length a. The maximum length a is defined as a distance between two end points on an edge of the crystal flat surface and farthest from each other. 8a/d35.

A red fluorescent substance includes an Mn-activated complex fluoride represented by the formula (1) below:

A.sup.1.sub.2MF.sub.6:Mn(1)

(wherein, letter M is one or two or more of tetravalent elements selected from Si, Ti, Zr, Hf, Ge, and Sn, with Ti or Ge being essential; and symbol A.sup.1 is one or two or more of alkali metals selected from Li, Na, K, Rb, and Cs, with at least one of Na, Rb, and Cs being essential). The red fluorescent substance has an emission spectrum having a peak between 600 to 650 nm, a fluorescent life time up to 5.0 milliseconds at room temperature, and an internal quantum efficiency at least 0.60 at the time of excitation at 450 nm.

Because of the short fluorescent life time, high emission intensity, and high emission efficiency, the red fluorescent substance is suitable for use in the display device that needs high-speed high-definition rendering.

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image. A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100 C. to the emission intensity at 25 C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.

The present invention provides a method for producing a fluoride fluorescent material, comprising: contacting a fluoride particles represented by the following general formula (I):

K.sub.2[M.sub.1-aMn.sup.4.sub.aF.sub.6](I)

wherein M is at least one member selected from the group consisting of elements belonging to Groups 4 and 14 of the Periodic Table, and a satisfies the relationship: 0<a<0.2; with a solution containing alkaline earth metal ions in the presence of a reducing agent to form an alkaline earth metal fluoride on the surface of the fluoride particles.

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image.

A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100 C. to the emission intensity at 25 C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.

The present invention provides a method for producing a fluoride fluorescent material, comprising: contacting a fluoride particles represented by the following general formula (I):
K.sub.2[M.sub.1-aMn.sup.4+.sub.aF.sub.6](I)
wherein M is at least one member selected from the group consisting of elements belonging to Groups 4 and 14 of the Periodic Table, and a satisfies the relationship: 0<a<0.2; with a solution containing alkaline earth metal ions in the presence of a reducing agent to form an alkaline earth metal fluoride on the surface of the fluoride particles.

The present invention relates to a method for producing a hexafluoromanganate(IV), said method being characterized by comprising: inserting an anode and a cathode into a reaction solution that contains a compound containing manganese having an atomic valence of less than 4 and/or manganese having an atomic valence of more than 4 and hydrogen fluoride; and then applying an electric current having an electric current density of 100 to 1000 A/m.sup.2 between the anode and the cathode. According to the present invention, it becomes possible to produce a hexafluoromanganate(IV) in which the content ratio of manganese having an atomic valence of 4 is high and the contamination with oxygen is reduced and which has high purity. When a complex fluoride red phosphor is produced using the hexafluoromanganate(IV) as a raw material, the phosphor produced has high luminescence properties, particularly high internal quantum efficiency.

According to one embodiment, a scintillator includes a host material having the chemical formula: A.sub.2BX.sub.6, where A includes a monovalent ion, B includes a tetravalent ion, and X includes a halide ion.

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image. A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100 C. to the emission intensity at 25 C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.